流量调节器-管路系统频率特性及稳定性

Frequency Characteristics and Stability of the Flow Regulator-Pipe System

针对某型流量调节器及管路系统,建立了描述其动态特性的频域分析模型,研究了系统在入口压力扰动下的频率响应特性以及系统的固有稳定性。结果表明系统响应的谐振频率反映了管路的声学特性,而调节器滑阀的作动,对谐振峰具有放大效果。通过分析系统在不同参数下的固有复频率,获得了系统稳定性边界随入口阻力的变化规律。当入口阻力由0向匹配阻力递增时,系统不稳定的区间不断缩小。当入口阻力超过某一值后,系统的不稳定区间消失。系统产生不稳定的机理是,在一定的频率范围内,流量调节器表现出负阻力特性,且当负阻力效果超过入口阻力耗散时,所在的频率范围就是系统的不稳定频率区间。若管路长度决定的系统固有振荡频率落入不稳定的频率区间内,则系统在此固有频率下产生不稳定。

A frequency-domain analytical model of one flow regulator-pipe system was developed to describe its dynamic characteristics. The system frequency response to inlet pressure disturbance and the system stability was investigated. The re- suits show that, the resonance frequencies of the system represent the acoustic characteristics of the pipe, and the movement of the slider enlarges the resonance amplitude. By analyzing the system complex natural frequency at different parameters, the variable rule of the system stable boundary according to the inlet resistance was presented. It shows that, as the inlet resistance increasing from zero to the matching resistance, the unstable region of the system reduced continually, and disappeared after the inlet resistance exceeding one value. The mechanism of system instability is that, the regulator works as a negative resist- ance component at a frequency range, which becomes the unstable frequency region when the negative resistance effect of the regulator exceeds the inlet resistance dissipation. And if the system natural frequency determined by the pipe length was in the unstable frequency region, then the instability takes place at the natural frequency.